1. Field of the Invention
Embodiments of the present invention relate to lower limb prostheses in general, and, in certain embodiments, to a low profile shock module prosthesis having a resilient element and a torque-resisting cuff permitting rotational compliance between the lower leg and foot.
2. Description of the Related Art
Various types of lower limb prostheses are known in the prior art. Such devices generally include some form of attachment for coupling the device to the dorsal end of the limb and for extending to the ground to provide body support. Moreover, these devices generally constitute attempts to simulate the structure and/or the performance of the human leg and foot.
The various prostheses known in the prior art include some prostheses designed for people who have long residual limbs. For these patients, the calf and shin functions as the stump for prosthetic purposes. Thus, any prosthetic device utilized by the patient must either be relatively compact so as to be attachable below the point of amputation, or must be configured to accommodate the patient's shin and calf while attached thereto or higher up on the wearer's leg.
Among the features desirable in a lower limb prosthesis is the incorporation of some means for providing impact absorption and/or dampening during use of the prosthesis, without sacrificing the ability to reliably and predictably support the amputee's body weight. Such impact absorption permits the amputee to participate in activities with comfort and minimal stump trauma, hence allowing the amputee to be mobile for longer periods of time. Also desirable is a convenient means to selectively adjust the degree of impact absorption to suit the particular attributes (e.g., weight) and activity (e.g., walking, running, jumping, etc.) of the amputee.
Another desirable feature of lower limb prostheses is the incorporation of some means for allowing rotational compliance of the lower leg and foot relative to the stump of the amputee. Such rotation is beneficial and simulates the action of a natural human knee/ankle in a number of activities that involve the twisting of a person's body with respect to their planted foot, such as golf, tennis, and the like. Unrestrained compliance, however, is undesirable, as the foot would be free to twist unnaturally. Thus, it is desirable to incorporate a means for providing torsion-resistance against the rotation of a lower leg and foot relative to the stump of the amputee, and for returning the foot to its natural forward orientation after each rotational movement.
Impact absorption in lower limb prostheses can be achieved through the use of two or more elongated telescoping members with a resilient means disposed therebetween. Axial forces acting on such members cause relative longitudinal motion between them with the resilient means providing energy storage and release. Due to the vertical height of some of the pylons, those shock-absorbing prostheses cannot accommodate the shin and calf of an amputee with a long residual limb.
Thus, although the prior art illustrates many impact absorbing prostheses, few, if any, are designed to be compact enough for use by patients with long residual limbs. Furthermore, none of the prior art sets forth a lower limb prosthesis for amputees with long residual limbs that can provide both impact absorption and rotational compliance with torsion-resistance.